1. Field of the Invention
The present invention relates to a refrigerating device, and in particular, to a refrigerating device which does not cause a large burden on the environment and which can remove a large amount of heat.
2. Description of the Related Art
Refrigerators, air conditioners, and refrigerating devices for automatic vending machines and showcases have usually used, as a conventional refrigerant, chlorofluorocarbon refrigerants such as dichlorodifluoromethane (CFC-12), or hydrochlorofluorocarbon refrigerants such as chlorodifluoromethane (HCFC-12). When these refrigerants are released into the atmosphere and reach the ozone layer above the earth, the problem of destruction of the ozone layer arises. Thus, use of chlorofluorocarbon flon and hydrochlorofluorocarbon flon, which are refrigerants which have been used until now in refrigerating devices, has been prohibited or restricted.
As a result, hydrofluorocarbon refrigerants such as CH2FCF3 (HFC-134a) have been used as a substitute flon of the above refrigerants. However, even with such HFC refrigerants, a problem arises in that the effect thereof on global warming, which is another global environmental issue, is near the same level as that of the conventional HCFC-22 (CHClF2) which is an HCFC refrigerant.
Further, in refrigerating devices which are equipped with a hot-water supply function in addition to the functions of heating and cooling, the condensation temperature of a conventional refrigerant cannot be made high, and as a result, only heat of about 80xc2x0 C. (the obtained hot water is about 50xc2x0 C.) can be removed at the heat releasing device. It is impossible to remove a high heat amount of, for example, 120xc2x0 C. (the obtained hot water is about 80xc2x0 C.), and a supplementary heat source such as an electric heater or the like is used in order to raise the temperature of the hot water.
In this way, a refrigerating device which does not result in a large burden on the environment and which can remove a large amount of heat has not yet been realized.
In view of the aforementioned, an object of the present invention is to provide a refrigerating device which does not cause a large burden on the environment, which enables a large amount of heat to be removed, and in which the return of the refrigerating device oil to the compressor is good.
Another object of the present invention is to provide a refrigerating device which can be used stably over a long period of time.
Yet another object of the present invention is to provide a refrigerating device in which the generation of rust or the like which is caused by the water included in the refrigerating circuit can be prevented.
The following refrigerating devices of the present invention are provided in order to achieve the above-described objects.
(1) A refrigerating device in which carbon dioxide is circulated as a refrigerant in a refrigerating circuit in which at least a refrigerant compressor, a heat releasing device, an expansion mechanism, and an evaporator are connected in an annular arrangement by refrigerant pipes, wherein a refrigerating device oil used in the compressor has a viscosity at 40xc2x0 C. of 5 to 300 cSt, a volume specific resistivity of 108 xcexa9xc2x7cm or more, and a pour point of xe2x88x9230xc2x0 C. or less when the carbon dioxide is dissolved to saturation.
(2) A refrigerating device in which carbon dioxide is circulated as a refrigerant in a refrigerating circuit in which at least a refrigerant compressor, a heat releasing device, an expansion mechanism, and an evaporator are connected in an annular arrangement by refrigerant pipes, wherein a refrigerating device oil used in the compressor has a viscosity at 40xc2x0 C. of 5 to 300 cSt, a volume specific resistivity of 108 xcexa9xc2x7cm or more, and a pour point of xe2x88x9230xc2x0 C. or less when the carbon dioxide is dissolved to saturation, and organic materials used in the refrigerating circuit are materials which are not physically and/or chemically altered by high-temperature, high-pressure carbon dioxide.
(3) A refrigerating device in which carbon dioxide is circulated as a refrigerant in a refrigerating circuit in which at least a refrigerant compressor, a heat releasing device, an expansion mechanism, and an evaporator are connected in an annular arrangement by refrigerant pipes, wherein a refrigerating device oil used in the compressor has a viscosity at 40xc2x0 C. of 5 to 300 cSt, a volume specific resistivity of 108 xcexa9xc2x7cm or more, and a pour point of xe2x88x9230xc2x0 C. or less when the carbon dioxide is dissolved to saturation, and the refrigerating circuit includes a drying device for trapping moisture within the refrigerating circuit.